The present invention relates to a special-effect-waveform generator used for, for example, a vide o sub-adjuster (production switcher), particularly to a special-effect-waveform generator for generating a wipe waveform used to synthesize a plurality of video pictures.
For example, special-effect-waveform generator for generating a wipe waveform adapted to a standard definition television (SDTV) or a high definition television (HDTV) has been known so far. A special-effect apparatus using the special-effect-waveform generator performs the processing concerned with levels and time at the stage of a video signal when displaying an image based on the video signal obtained by picking up the signal with a television camera on a screen and thus, the apparatus is used to obtain a desired video effect.
Several apparatuses for generating a special effect are disclosed in the following official gazettes. For example, the official gazette of Japanese Patent Laid-Open No. 102068/1985 discloses a xe2x80x9cspecial-effect apparatusxe2x80x9d. The special-effect apparatus is provided with two DVE (Digital Video Effect) units corresponding to each of video signals of two channels so as to obtain two-channel DVE interlocking effect by supplying wipe waveforms having polarities different from each other generated by a waveform generator to respective DVE unit. In the official gazette of Japanese Patent Laid-Open No. 102068/1985, a special-effect-waveform generator is shown as a waveform generator but the structure of the waveform generator is not disclosed.
Moreover, the official gazette of Japanese Patent Laid-Open No. 220570/1986 discloses a xe2x80x9cspecial-effect-waveform generatorxe2x80x9d. The special-effect-waveform generator is constituted so as to solve the problem that, when synthesizing a contracted image generated in accordance with an input key signal and a video signal by using the same key signal, a phase shift occurs between the image and the signal because it takes a lot of time to contract the image and thereby, it is impossible to follow the quick operation of a fader. The special-effect-waveform generator eliminates the phase shift by generating two effect waveforms whose delay times are different from each other for a fader control signal, generates contracted images by using one effect waveform, and synthesizes the images by using the other effect waveform.
Furthermore, the official gazette of Japanese Patent Laid-Open No. 123280/1988 discloses a xe2x80x9cdigital special-effect apparatusxe2x80x9d. The digital special-effect apparatus makes it possible to completely interlock a video signal with a key signal by processing the signals with a digital special-effect circuit.
Furthermore, the official gazette of Japanese Patent Publication No. 12149/1989 discloses a xe2x80x9cspecial-effect waveform controllerxe2x80x9d. According to the special-effect waveform controller, it is possible to cut out a screen at any position of each special-effect waveform and obtain waveform-size data in which the waveform size does not change even if a positioner changes in the middle of a fader.
Furthermore, the official gazette of Japanese Patent Publication No. 26229/1989 discloses a xe2x80x9cvideo special-effect signal generatorxe2x80x9d. The video special-effect signal generator makes it possible to provide many horizontal basic waves and vertical basic waves by constituting a memory for storing horizontal and vertical basic waves with an erasable memory so as to be able to store the waveform data generated by a central processing unit.
Problems to be Solved by the Invention:
However, an art for generating a special-effect waveform capable of corresponding to a plurality of television systems is not disclosed in any one of the above official gazettes of Japanese Patent Laid-Open Nos. 220570/1986 and 123280/1989 and Japanese Patent Publication Nos. 12149/1989 and 26229/1989. Thus, because a conventional special-effect-waveform generator is constituted exclusively for each television system such as the SDTV or HDTV, there is a problem that the production efficiency is low. Therefore, it is desired to develop a special-effect-waveform generator that can be used for these television systems in common.
Furthermore, an extended definition television (EDTV) obtained by improving the SDTV has been recently developed and a second-generation EDTV-2 in which the aspect ratio is particularly extended to 4:3 or more is practically used. Therefore, it is desired to develop a special-effect-waveform generator capable of also corresponding to the xe2x80x9c4:2:0pxe2x80x9d system of the EDTV-2 in addition to the above SDTV and HDTV.
The present invention is made to meet the above requests and its object is to provide a special-effect-waveform generator capable of corresponding to signal formats of various television systems such as the SDTV, EDTV-2, and HDTV.
To achieve the above object, the special-effect-waveform generator of the first mode of the present invention comprises:
a pulse generation circuit for generating a control pulse used to generate waveform data for constituting a special-effect waveform suitable for a signal format designated from an external unit;
a basic-wave generation circuit for generating waveform data for constituting a basic wave in accordance with the control pulse output from the pulse generation circuit;
an interpolation circuit for interpolating the waveform data for constituting the basic wave generated by the basic-wave generation circuit; and
a selection circuit for selecting either of the waveform data interpolated by the interpolation circuit and the waveform data output from the basic-wave generation circuit in accordance with the signal format and outputting the selected waveform data as the waveform data for constituting a special-effect waveform.
The special-effect-waveform generator of the first mode outputs the waveform data for constituting a basic wave as the waveform data for constituting a special-effect waveform when the signal format for the SDTV is designated. Moreover, the generator outputs the waveform data in which the waveform data for constituting a basic wave is interpolated as the waveform data for constituting a special-effect waveform when the signal format for the HDTV is designated.
Therefore, when a device cannot operate because the frequency of a clock pulse is too high like a signal for the HDTV, it is possible to obtain a waveform same as the case of the device operated at the frequency of the original clock pulse through interpolation by operating the device at a frequency half the frequency of a clock pulse. Therefore, the special-effect-waveform generator of the first mode is able to correspond to both the SDTV and HDTV without requiring special hardware.
Moreover, for the same purpose, the special-effect-waveform generator of the second mode of the present invention comprises:
a pulse generation circuit for generating a control pulse used to generate waveform data for constituting a special-effect waveform suitable for a signal format designated from an external unit;
a basic-wave generation circuit for generating waveform data for constituting a basic wave in accordance with the control pulse output from the pulse generation circuit; and
a line memory for rearranging the waveform data for constituting the basic wave generated by the basic-wave generation circuit and outputting the rearranged waveform data as the waveform data for constituting a special-effect waveform.
The special-effect-waveform generator of the second mode outputs the waveform data for constituting a basic wave as the waveform data for constituting a special-effect waveform when the signal format for the SDTV is designated, similarly to the case of the special-effect-waveform generator of the first mode. Moreover, the generator outputs the waveform data generated by rearranging the waveform data for constituting a basic wave with a line memory as the waveform data for constituting a special-effect waveform when the signal format for the EDTV-2 is designated.
Therefore, because the special-effect-waveform generator of the second mode is able to correspond to the xe2x80x9c4:2:0pxe2x80x9d system corresponding to the progressive scan system for the EDTV-2, the generator is able to correspond to both SDTV signal and EDTV-2 signal.
Moreover, for the same purpose, the special-effect-waveform generator of the third mode of the present invention comprises:
a pulse generation circuit for generating a control pulse used to generate waveform data for constituting a special-effect waveform suitable for a signal format designated from an external unit;
a basic-wave generation circuit for generating waveform data for constituting a basic wave in accordance with the control pulse output from the pulse generation circuit;
an interpolation circuit for interpolating the waveform data for constituting the basic wave generated by the basic-wave generation circuit;
a selection circuit for selecting either of the waveform data interpolated by the interpolation circuit and the waveform data output from the basic-wave generation circuit in accordance with the signal format; and
a line memory for rearranging the waveform data output from the selection circuit and outputting the rearranged waveform data as a special-effect waveform.
The special-effect-waveform generator of the third mode outputs a basic signal as a special-effect waveform when the signal format for the SDTV is designated, the waveform data in which a basic wave is interpolated as a special-effect waveform when a signal format for the HDTV is designated, and a waveform generated by rearranging the waveform data for constituting a basic wave as a special-effect waveform when the signal format for the EDTV-2 is designated. Therefore, the special-effect-waveform generator of the third mode is able to correspond to any one of the SDTV, HDTV, and EDTV-2.
In the case of the special-effect-waveform generators of the first and second modes, the selection circuit can be constituted so as to alternately select the waveform data output from the basic waveform generation circuit and the waveform data output from the interpolation circuit when the waveform data interpolated by the interpolation circuit in accordance with any one of the signal formats is selected and thereby, output the selected waveform data as the waveform data for constituting a special-effect waveform.
According to the above structure, it is possible to correspond to the four-layer-divided HDTV processing through the same control by using an interpolation circuit. That is, when performing the four-layer-divided processing at the time of the HDTV, it is possible to operate four circuits of the SDTV through completely the same control. This is because it is unnecessary to change the level difference between Y1 and Y2 with control data since interpolation is used though waveform data is generated by using a clock of 37.125 MHz in the above Y1 and Y2 layers.
Moreover, the special-effect-waveform generators of the second and third modes can be constituted so that the line memory is constituted with a first line memory and a second line memory, the first line memory successively stores the waveform data output from the selection circuit for the first half horizontal period, the second line memory successively stores the waveform data output from the selection circuit for the next half horizontal period, and thereafter the content in the first line memory and the content in the second line memory are alternately read. According to the above structure, it is possible to minimize the number of line memories used.